1. Field of the Invention
The present invention relates to a data recording medium such as a digital video disk or digital versatile disk (DVD) that retains data for individually selecting a plurality of contents such as pieces of music to replay and to a data replay apparatus for replaying data on such a recording medium.
2. Description of the Related Art
A DVD and a DVD player have been practically utilized. A DVD is an optical disk for recording digitized video and audio data. Of replaying data on a DVD and recording data onto a DVD, a DVD player performs at least replaying data.
In the DVD format (standard), the format of still picture called subpicture that may be overlaid on a moving picture is defined besides normal moving pictures coded in Moving Picture Experts Group (MPEG) 2. A DVD implements a caption (subtitle) of a movie and a menu with such a subpicture.
In the DVD format, a specific programming language called navigation command is provided for controlling a replay method of a DVD player. Programming in navigation command implements, for example, an interactive program (software) and a replay started at a specific point called chapter such as the start of a highlight scene or a break in a story in a movie or a track on a compact disk (CD) that indicates a break between pieces of music.
An interactive program as mentioned above requires a user-operable picture for interactive questions and answers.
An interactive operation of a DVD player is usually implemented through indirect manipulation by the viewer selecting operation buttons displayed on a menu with cursor keys and so on of a remote controller, instead of direct interactive manipulation using operation buttons of the DVD player or the remote controller. As a result, various types of interactive software may be provided without being restricted by the buttons dedicated to the hardware of the DVD player.
Among menus for such interactive operations, basic ones common to any DVD are defined as DVD system menus. The DVD system menus are frames called up by a viewer through operation of the menu button of the remote controller of the DVD player for replaying a DVD in the DVD player. The format provides that the menu button is required to be added to the remote controller. The DVD system menus include operation buttons displayed on the screen. Various replay patterns are achieved by the viewer through selecting the operation buttons with a cursor key. The format provides that the cursor key is required to be added to the remote controller.
Multiplexed video and audio data as a content of a DVD is called video object (VOB). A VOB is made up of a meaningful series of multiplexed video and audio data and defined as multiplexed data that makes a great sense in allowing access for a continuous replay such as a title of movie, the audio menu or the chapter menu. Each VOB has a serial VOB identification number. The VOB is further divided into units called cells. The cells each have a cell identification number in ascending order. The cells are each defined as a meaningful block as in defining the VOB. For example, the cells correspond to divisions of chapters of a movie title or to pages to be displayed of a menu with a plurality of pages.
According to the DVD format, a unit in which a menu or a title is replayed is represented by replay control data called program chain (PGC). A PGC includes a pre-command (PRE CMD) and a post-command (POST CMD) as navigation commands and VOB identifier (VOB ID). The VOB ID is made up of a combination of the VOB ID number described above and the initial address on the disk where the corresponding VOB is recorded. The VOB ID further includes cell information sections. As the VOB ID, each cell information section is composed of a combination of cell ID number in the VOB and the initial address on the disk where the corresponding cell is recorded, and a cell command (cell CMD) as a navigation command executed at the point of completion of replay of the cell.
A replay of a DVD is thus controlled by such a PGC data structure. In other words, a player is allowed to perform a series of meaningful replay as long as a PGC is included. The DVD format thus defines a single PGC or a plurality of PGCs as xe2x80x98titlexe2x80x99.
According to the authoring guidebook published by the DVD consortium, it is recommended that pieces of music (tunes) are sectioned from one another so that each piece corresponds to a title to replay in the case of a musical product such as a karaoke, in particular, for replaying tunes one by one. Accordingly, a related-art DVD on the market for a musical product is, in general, made up of PGCs whose number corresponds to the number of tunes, one of the PGCs representing one title, that is, one tune. In the post CMD of each PGC, an instruction is written to jump to a menu. Such a structure allows easy authoring since only one type of PGC structure is required regardless of the number of tunes recorded on the DVD.
On the other hand, the data structure described above has the following three problems.
(1) The data structure does not allow fast forward and fast reverse across tunes that are achieved by replay of a conventional laser disk or a video compact disk (CD). The reason is as follows. The DVD format prohibits a direct access across PGCs during a replay by a DVD player, that is, a shift or jump to another PGC while one PGC is being replayed. Therefore the data structure described above does not allow fast forward and fast reverse (or reverse) across tunes. In the data structure, if fast forward is performed, for example, the post CMD is executed at the end of the tune and the status shifts to the menu for tune selection. If fast reverse is performed, a replay of the tune is started at the instant of returning to the start of the tune and the operation of the fast reverse key is disabled.
(2) In a DVD player the data structure does not allow a skip for stopping the replay of the tune being currently replayed and jumping to the start of the next tune or returning to the start of the immediately preceding tune. The reason is as follows. The DVD format defines a skip implemented by a next skip key or a previous skip key as the function of jumping to next or previous part of title (PTT) included in one PGC. The PTT is defined as a single cell or a series of cells. In the data structure described above, however, the PGC being replayed by the DVD player only includes the cell corresponding to the tune being replayed. If the cell is defined as PTT, the DVD player finds no destination since the next or previous tune is PTT included in another PGC. The operation of the next skip key or the previous skip key is thus disabled.
(3) The data structure does not allow random access for jumping to a specific point in a specific tune by inputting time at which a replay is started. The reason is as follows. The DVD format defines that a display of replay time of a DVD player is made through adding up the replay time of the individual cells in sequence in the PGC. Consequently, the replay time display is reset to zero at the start point of each PGC and no display is provided for indicating the elapsed replay time throughout the disk. Therefore, random access to a specific point in a specific tune by inputting time at which a replay is started is not achieved.
It is an object of the invention to provide a data recording medium and a data replay apparatus for allowing an automatic return to a menu at the completion point of a replay of one content and allowing an arbitrary jump to the next or previous content during a replay of one content.
A data recording medium of the invention retains data for individually selecting a plurality of contents and replaying each of the contents. The medium includes: a plurality of content data items sectioned so as to each correspond to the respective contents and representing the respective contents; a replay control data item for controlling replay of the content data items; and a menu control data item for displaying a menu for individually selecting the contents and instructing to replay by the replay control data item. The replay control data item has a data structure that allows a shift from a state of replay of a specific one of the contents to a state of replay of another one of the contents, and a data structure that includes an instruction data item executed only during a normal replay for instructing to display the menu by the menu control data item after the replay of the content data item is completed.
A data replay apparatus of the invention is used for a data recording medium including: a plurality of content data items sectioned so as to each correspond to the respective contents and representing the respective contents; a replay control data item for controlling replay of the content data items; and a menu control data item for displaying a menu for individually selecting the contents and instructing to replay by the replay control data item; wherein the replay control data item has a data structure that allows a shift from a state of replay of a specific one of the contents to a state of replay of another one of the contents, and a data structure that includes an instruction data item executed only during a normal replay for instructing to display the menu by the menu control data item after the replay of the content data item is completed. The apparatus replays the content data items and comprises: a menu display means for displaying the menu by using the menu control data item; a replay instruction means for instructing to replay by individually selecting a specific one of the contents by using the menu displayed by the menu display means and for instructing to change the state of replay including a shift from the state of replay of the specific one of the contents to a state of replay of another one of the contents; a content replay means for replaying the content data item by using the menu control data item and the replay control data item, following the instruction given by the replay instruction means; and a menu display instruction means for having the menu display means display the menu based on the instruction data item of the replay control data item after the replay of the content data item by the content replay means is completed.
According to the data recording medium of the invention, the plurality of content data items sectioned so as to each correspond to the respective contents and representing the respective contents are controlled by the replay control data item and replayed. The menu control data item displays the menu for individually selecting the contents and instructing to replay by the replay control data item. The replay control data item allows a shift from a state of replay of a specific one of the contents to a state of replay of another one of the contents. Only during a normal replay the instruction data item instructs to display the menu by the menu control data item after the replay of the content data item is completed.
According to the data replay apparatus of the invention, the menu display means displays the menu by using the menu control data item. The replay instruction means instructs to replay by individually selecting a specific one of the contents by using the menu displayed by the menu display means and instructs to change the state of replay including a shift from the state of replay of the specific one of the contents to a state of replay of another one of the contents. The content replay means replays the content data item by using the menu control data item and the replay control data item, following the instruction given by the replay instruction means. The menu display instruction means has the menu display means display the menu based on the instruction data item of the replay control data item after the replay of the content data item by the content replay means is completed.
Other and further objects, features and advantages of the invention will appear more fully from the following description.